<?php
/**
 * CWebUser class file
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.yiiframework.com/
 * @copyright 2008-2013 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

/**
 * CWebUser represents the persistent state for a Web application user.
 *
 * CWebUser is used as an application component whose ID is 'user'.
 * Therefore, at any place one can access the user state via
 * <code>Yii::app()->user</code>.
 *
 * CWebUser should be used together with an {@link IUserIdentity identity}
 * which implements the actual authentication algorithm.
 *
 * A typical authentication process using CWebUser is as follows:
 * <ol>
 * <li>The user provides information needed for authentication.</li>
 * <li>An {@link IUserIdentity identity instance} is created with the user-provided information.</li>
 * <li>Call {@link IUserIdentity::authenticate} to check if the identity is valid.</li>
 * <li>If valid, call {@link CWebUser::login} to login the user, and
 *     Redirect the user browser to {@link returnUrl}.</li>
 * <li>If not valid, retrieve the error code or message from the identity
 * instance and display it.</li>
 * </ol>
 *
 * The property {@link id} and {@link name} are both identifiers
 * for the user. The former is mainly used internally (e.g. primary key), while
 * the latter is for display purpose (e.g. username). The {@link id} property
 * is a unique identifier for a user that is persistent
 * during the whole user session. It can be a username, or something else,
 * depending on the implementation of the {@link IUserIdentity identity class}.
 *
 * Both {@link id} and {@link name} are persistent during the user session.
 * Besides, an identity may have additional persistent data which can
 * be accessed by calling {@link getState}.
 * Note, when {@link allowAutoLogin cookie-based authentication} is enabled,
 * all these persistent data will be stored in cookie. Therefore, do not
 * store password or other sensitive data in the persistent storage. Instead,
 * you should store them directly in session on the server side if needed.
 *
 * @property boolean $isGuest Whether the current application user is a guest.
 * @property mixed $id The unique identifier for the user. If null, it means the user is a guest.
 * @property string $name The user name. If the user is not logged in, this will be {@link guestName}.
 * @property string $returnUrl The URL that the user should be redirected to after login.
 * @property string $stateKeyPrefix A prefix for the name of the session variables storing user session data.
 * @property array $flashes Flash messages (key => message).
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package system.web.auth
 * @since 1.0
 */
class CWebUser extends CApplicationComponent implements IWebUser
{
    const FLASH_KEY_PREFIX = 'Yii.CWebUser.flash.';
    const FLASH_COUNTERS = 'Yii.CWebUser.flashcounters';
    const STATES_VAR = '__states';
    const AUTH_TIMEOUT_VAR = '__timeout';
    const AUTH_ABSOLUTE_TIMEOUT_VAR = '__absolute_timeout';

    /**
     * @var boolean whether to enable cookie-based login. Defaults to false.
     */
    public $allowAutoLogin = false;
    /**
     * @var string the name for a guest user. Defaults to 'Guest'.
     * This is used by {@link getName} when the current user is a guest (not authenticated).
     */
    public $guestName = 'Guest';
    /**
     * @var string|array the URL for login. If using array, the first element should be
     * the route to the login action, and the rest name-value pairs are GET parameters
     * to construct the login URL (e.g. array('/site/login')). If this property is null,
     * a 403 HTTP exception will be raised instead.
     * @see CController::createUrl
     */
    public $loginUrl = array('/site/login');
    /**
     * @var array the property values (in name-value pairs) used to initialize the identity cookie.
     * Any property of {@link CHttpCookie} may be initialized.
     * This property is effective only when {@link allowAutoLogin} is true.
     */
    public $identityCookie;
    /**
     * @var integer timeout in seconds after which user is logged out if inactive.
     * If this property is not set, the user will be logged out after the current session expires
     * (c.f. {@link CHttpSession::timeout}).
     * @since 1.1.7
     */
    public $authTimeout;
    /**
     * @var integer timeout in seconds after which user is logged out regardless of activity.
     * @since 1.1.14
     */
    public $absoluteAuthTimeout;
    /**
     * @var boolean whether to automatically renew the identity cookie each time a page is requested.
     * Defaults to false. This property is effective only when {@link allowAutoLogin} is true.
     * When this is false, the identity cookie will expire after the specified duration since the user
     * is initially logged in. When this is true, the identity cookie will expire after the specified duration
     * since the user visits the site the last time.
     * @see allowAutoLogin
     * @since 1.1.0
     */
    public $autoRenewCookie = false;
    /**
     * @var boolean whether to automatically update the validity of flash messages.
     * Defaults to true, meaning flash messages will be valid only in the current and the next requests.
     * If this is set false, you will be responsible for ensuring a flash message is deleted after usage.
     * (This can be achieved by calling {@link getFlash} with the 3rd parameter being true).
     * @since 1.1.7
     */
    public $autoUpdateFlash = true;
    /**
     * @var string value that will be echoed in case that user session has expired during an ajax call.
     * When a request is made and user session has expired, {@link loginRequired} redirects to {@link loginUrl} for login.
     * If that happens during an ajax call, the complete HTML login page is returned as the result of that ajax call. That could be
     * a problem if the ajax call expects the result to be a json array or a predefined string, as the login page is ignored in that case.
     * To solve this, set this property to the desired return value.
     *
     * If this property is set, this value will be returned as the result of the ajax call in case that the user session has expired.
     * @since 1.1.9
     * @see loginRequired
     */
    public $loginRequiredAjaxResponse;

    private $_keyPrefix;
    private $_access = array();

    /**
     * PHP magic method.
     * This method is overriden so that persistent states can be accessed like properties.
     * @param string $name property name
     * @return mixed property value
     */
    public function __get($name)
    {
        if ($this->hasState($name))
            return $this->getState($name);
        else
            return parent::__get($name);
    }

    /**
     * PHP magic method.
     * This method is overriden so that persistent states can be set like properties.
     * @param string $name property name
     * @param mixed $value property value
     */
    public function __set($name, $value)
    {
        if ($this->hasState($name))
            $this->setState($name, $value);
        else
            parent::__set($name, $value);
    }

    /**
     * PHP magic method.
     * This method is overriden so that persistent states can also be checked for null value.
     * @param string $name property name
     * @return boolean
     */
    public function __isset($name)
    {
        if ($this->hasState($name))
            return $this->getState($name) !== null;
        else
            return parent::__isset($name);
    }

    /**
     * PHP magic method.
     * This method is overriden so that persistent states can also be unset.
     * @param string $name property name
     * @throws CException if the property is read only.
     */
    public function __unset($name)
    {
        if ($this->hasState($name))
            $this->setState($name, null);
        else
            parent::__unset($name);
    }

    /**
     * Initializes the application component.
     * This method overrides the parent implementation by starting session,
     * performing cookie-based authentication if enabled, and updating the flash variables.
     */
    public function init()
    {
        parent::init();
        Yii::app()->getSession()->open();
        if ($this->getIsGuest() && $this->allowAutoLogin)
            $this->restoreFromCookie();
        elseif ($this->autoRenewCookie && $this->allowAutoLogin)
            $this->renewCookie();
        if ($this->autoUpdateFlash)
            $this->updateFlash();

        $this->updateAuthStatus();
    }

    /**
     * Logs in a user.
     *
     * The user identity information will be saved in storage that is
     * persistent during the user session. By default, the storage is simply
     * the session storage. If the duration parameter is greater than 0,
     * a cookie will be sent to prepare for cookie-based login in future.
     *
     * Note, you have to set {@link allowAutoLogin} to true
     * if you want to allow user to be authenticated based on the cookie information.
     *
     * @param IUserIdentity $identity the user identity (which should already be authenticated)
     * @param integer $duration number of seconds that the user can remain in logged-in status. Defaults to 0, meaning login till the user closes the browser.
     * If greater than 0, cookie-based login will be used. In this case, {@link allowAutoLogin}
     * must be set true, otherwise an exception will be thrown.
     * @return boolean whether the user is logged in
     */
    public function login($identity, $duration = 0)
    {
        $id = $identity->getId();
        $states = $identity->getPersistentStates();
        if ($this->beforeLogin($id, $states, false)) {
            $this->changeIdentity($id, $identity->getName(), $states);

            if ($duration > 0) {
                if ($this->allowAutoLogin)
                    $this->saveToCookie($duration);
                else
                    throw new CException(Yii::t('yii', '{class}.allowAutoLogin must be set true in order to use cookie-based authentication.',
                        array('{class}' => get_class($this))));
            }

            if ($this->absoluteAuthTimeout)
                $this->setState(self::AUTH_ABSOLUTE_TIMEOUT_VAR, time() + $this->absoluteAuthTimeout);
            $this->afterLogin(false);
        }
        return !$this->getIsGuest();
    }

    /**
     * Logs out the current user.
     * This will remove authentication-related session data.
     * If the parameter is true, the whole session will be destroyed as well.
     * @param boolean $destroySession whether to destroy the whole session. Defaults to true. If false,
     * then {@link clearStates} will be called, which removes only the data stored via {@link setState}.
     */
    public function logout($destroySession = true)
    {
        if ($this->beforeLogout()) {
            if ($this->allowAutoLogin) {
                Yii::app()->getRequest()->getCookies()->remove($this->getStateKeyPrefix());
                if ($this->identityCookie !== null) {
                    $cookie = $this->createIdentityCookie($this->getStateKeyPrefix());
                    $cookie->value = null;
                    $cookie->expire = 0;
                    Yii::app()->getRequest()->getCookies()->add($cookie->name, $cookie);
                }
            }
            if ($destroySession)
                Yii::app()->getSession()->destroy();
            else
                $this->clearStates();
            $this->_access = array();
            $this->afterLogout();
        }
    }

    /**
     * Returns a value indicating whether the user is a guest (not authenticated).
     * @return boolean whether the current application user is a guest.
     */
    public function getIsGuest()
    {
        return $this->getState('__id') === null;
    }

    /**
     * Returns a value that uniquely represents the user.
     * @return mixed the unique identifier for the user. If null, it means the user is a guest.
     */
    public function getId()
    {
        return $this->getState('__id');
    }

    /**
     * @param mixed $value the unique identifier for the user. If null, it means the user is a guest.
     */
    public function setId($value)
    {
        $this->setState('__id', $value);
    }

    /**
     * Returns the unique identifier for the user (e.g. username).
     * This is the unique identifier that is mainly used for display purpose.
     * @return string the user name. If the user is not logged in, this will be {@link guestName}.
     */
    public function getName()
    {
        if (($name = $this->getState('__name')) !== null)
            return $name;
        else
            return $this->guestName;
    }

    /**
     * Sets the unique identifier for the user (e.g. username).
     * @param string $value the user name.
     * @see getName
     */
    public function setName($value)
    {
        $this->setState('__name', $value);
    }

    /**
     * Returns the URL that the user should be redirected to after successful login.
     * This property is usually used by the login action. If the login is successful,
     * the action should read this property and use it to redirect the user browser.
     * @param string $defaultUrl the default return URL in case it was not set previously. If this is null,
     * the application entry URL will be considered as the default return URL.
     * @return string the URL that the user should be redirected to after login.
     * @see loginRequired
     */
    public function getReturnUrl($defaultUrl = null)
    {
        if ($defaultUrl === null) {
            $defaultReturnUrl = Yii::app()->getUrlManager()->showScriptName ? Yii::app()->getRequest()->getScriptUrl() : Yii::app()->getRequest()->getBaseUrl() . '/';
        } else {
            $defaultReturnUrl = CHtml::normalizeUrl($defaultUrl);
        }
        return $this->getState('__returnUrl', $defaultReturnUrl);
    }

    /**
     * @param string $value the URL that the user should be redirected to after login.
     */
    public function setReturnUrl($value)
    {
        $this->setState('__returnUrl', $value);
    }

    /**
     * Redirects the user browser to the login page.
     * Before the redirection, the current URL (if it's not an AJAX url) will be
     * kept in {@link returnUrl} so that the user browser may be redirected back
     * to the current page after successful login. Make sure you set {@link loginUrl}
     * so that the user browser can be redirected to the specified login URL after
     * calling this method.
     * After calling this method, the current request processing will be terminated.
     */
    public function loginRequired()
    {
        $app = Yii::app();
        $request = $app->getRequest();

        if (!$request->getIsAjaxRequest()) {
            $this->setReturnUrl($request->getUrl());
            if (($url = $this->loginUrl) !== null) {
                if (is_array($url)) {
                    $route = isset($url[0]) ? $url[0] : $app->defaultController;
                    $url = $app->createUrl($route, array_splice($url, 1));
                }
                $request->redirect($url);
            }
        } elseif (isset($this->loginRequiredAjaxResponse)) {
            echo $this->loginRequiredAjaxResponse;
            Yii::app()->end();
        }

        throw new CHttpException(403, Yii::t('yii', 'Login Required'));
    }

    /**
     * This method is called before logging in a user.
     * You may override this method to provide additional security check.
     * For example, when the login is cookie-based, you may want to verify
     * that the user ID together with a random token in the states can be found
     * in the database. This will prevent hackers from faking arbitrary
     * identity cookies even if they crack down the server private key.
     * @param mixed $id the user ID. This is the same as returned by {@link getId()}.
     * @param array $states a set of name-value pairs that are provided by the user identity.
     * @param boolean $fromCookie whether the login is based on cookie
     * @return boolean whether the user should be logged in
     * @since 1.1.3
     */
    protected function beforeLogin($id, $states, $fromCookie)
    {
        return true;
    }

    /**
     * This method is called after the user is successfully logged in.
     * You may override this method to do some postprocessing (e.g. log the user
     * login IP and time; load the user permission information).
     * @param boolean $fromCookie whether the login is based on cookie.
     * @since 1.1.3
     */
    protected function afterLogin($fromCookie)
    {
    }

    /**
     * This method is invoked when calling {@link logout} to log out a user.
     * If this method return false, the logout action will be cancelled.
     * You may override this method to provide additional check before
     * logging out a user.
     * @return boolean whether to log out the user
     * @since 1.1.3
     */
    protected function beforeLogout()
    {
        return true;
    }

    /**
     * This method is invoked right after a user is logged out.
     * You may override this method to do some extra cleanup work for the user.
     * @since 1.1.3
     */
    protected function afterLogout()
    {
    }

    /**
     * Populates the current user object with the information obtained from cookie.
     * This method is used when automatic login ({@link allowAutoLogin}) is enabled.
     * The user identity information is recovered from cookie.
     * Sufficient security measures are used to prevent cookie data from being tampered.
     * @see saveToCookie
     */
    protected function restoreFromCookie()
    {
        $app = Yii::app();
        $request = $app->getRequest();
        $cookie = $request->getCookies()->itemAt($this->getStateKeyPrefix());
        if ($cookie && !empty($cookie->value) && is_string($cookie->value) && ($data = $app->getSecurityManager()->validateData($cookie->value)) !== false) {
            $data = @unserialize($data);
            if (is_array($data) && isset($data[0], $data[1], $data[2], $data[3])) {
                list($id, $name, $duration, $states) = $data;
                if ($this->beforeLogin($id, $states, true)) {
                    $this->changeIdentity($id, $name, $states);
                    if ($this->autoRenewCookie) {
                        $this->saveToCookie($duration);
                    }
                    $this->afterLogin(true);
                }
            }
        }
    }

    /**
     * Renews the identity cookie.
     * This method will set the expiration time of the identity cookie to be the current time
     * plus the originally specified cookie duration.
     * @since 1.1.3
     */
    protected function renewCookie()
    {
        $request = Yii::app()->getRequest();
        $cookies = $request->getCookies();
        $cookie = $cookies->itemAt($this->getStateKeyPrefix());
        if ($cookie && !empty($cookie->value) && ($data = Yii::app()->getSecurityManager()->validateData($cookie->value)) !== false) {
            $data = @unserialize($data);
            if (is_array($data) && isset($data[0], $data[1], $data[2], $data[3])) {
                $this->saveToCookie($data[2]);
            }
        }
    }

    /**
     * Saves necessary user data into a cookie.
     * This method is used when automatic login ({@link allowAutoLogin}) is enabled.
     * This method saves user ID, username, other identity states and a validation key to cookie.
     * These information are used to do authentication next time when user visits the application.
     * @param integer $duration number of seconds that the user can remain in logged-in status. Defaults to 0, meaning login till the user closes the browser.
     * @see restoreFromCookie
     */
    protected function saveToCookie($duration)
    {
        $app = Yii::app();
        $cookie = $this->createIdentityCookie($this->getStateKeyPrefix());
        $cookie->expire = time() + $duration;
        $data = array(
            $this->getId(),
            $this->getName(),
            $duration,
            $this->saveIdentityStates(),
        );
        $cookie->value = $app->getSecurityManager()->hashData(serialize($data));
        $app->getRequest()->getCookies()->add($cookie->name, $cookie);
    }

    /**
     * Creates a cookie to store identity information.
     * @param string $name the cookie name
     * @return CHttpCookie the cookie used to store identity information
     */
    protected function createIdentityCookie($name)
    {
        $cookie = new CHttpCookie($name, '');
        if (is_array($this->identityCookie)) {
            foreach ($this->identityCookie as $name => $value)
                $cookie->$name = $value;
        }
        return $cookie;
    }

    /**
     * @return string a prefix for the name of the session variables storing user session data.
     */
    public function getStateKeyPrefix()
    {
        if ($this->_keyPrefix !== null)
            return $this->_keyPrefix;
        else
            return $this->_keyPrefix = md5('Yii.' . get_class($this) . '.' . Yii::app()->getId());
    }

    /**
     * @param string $value a prefix for the name of the session variables storing user session data.
     */
    public function setStateKeyPrefix($value)
    {
        $this->_keyPrefix = $value;
    }

    /**
     * Returns the value of a variable that is stored in user session.
     *
     * This function is designed to be used by CWebUser descendant classes
     * who want to store additional user information in user session.
     * A variable, if stored in user session using {@link setState} can be
     * retrieved back using this function.
     *
     * @param string $key variable name
     * @param mixed $defaultValue default value
     * @return mixed the value of the variable. If it doesn't exist in the session,
     * the provided default value will be returned
     * @see setState
     */
    public function getState($key, $defaultValue = null)
    {
        $key = $this->getStateKeyPrefix() . $key;
        return isset($_SESSION[$key]) ? $_SESSION[$key] : $defaultValue;
    }

    /**
     * Stores a variable in user session.
     *
     * This function is designed to be used by CWebUser descendant classes
     * who want to store additional user information in user session.
     * By storing a variable using this function, the variable may be retrieved
     * back later using {@link getState}. The variable will be persistent
     * across page requests during a user session.
     *
     * @param string $key variable name
     * @param mixed $value variable value
     * @param mixed $defaultValue default value. If $value===$defaultValue, the variable will be
     * removed from the session
     * @see getState
     */
    public function setState($key, $value, $defaultValue = null)
    {
        $key = $this->getStateKeyPrefix() . $key;
        if ($value === $defaultValue)
            unset($_SESSION[$key]);
        else
            $_SESSION[$key] = $value;
    }

    /**
     * Returns a value indicating whether there is a state of the specified name.
     * @param string $key state name
     * @return boolean whether there is a state of the specified name.
     */
    public function hasState($key)
    {
        $key = $this->getStateKeyPrefix() . $key;
        return isset($_SESSION[$key]);
    }

    /**
     * Clears all user identity information from persistent storage.
     * This will remove the data stored via {@link setState}.
     */
    public function clearStates()
    {
        $keys = array_keys($_SESSION);
        $prefix = $this->getStateKeyPrefix();
        $n = strlen($prefix);
        foreach ($keys as $key) {
            if (!strncmp($key, $prefix, $n))
                unset($_SESSION[$key]);
        }
    }

    /**
     * Returns all flash messages.
     * This method is similar to {@link getFlash} except that it returns all
     * currently available flash messages.
     * @param boolean $delete whether to delete the flash messages after calling this method.
     * @return array flash messages (key => message).
     * @since 1.1.3
     */
    public function getFlashes($delete = true)
    {
        $flashes = array();
        $prefix = $this->getStateKeyPrefix() . self::FLASH_KEY_PREFIX;
        $keys = array_keys($_SESSION);
        $n = strlen($prefix);
        foreach ($keys as $key) {
            if (!strncmp($key, $prefix, $n)) {
                $flashes[substr($key, $n)] = $_SESSION[$key];
                if ($delete)
                    unset($_SESSION[$key]);
            }
        }
        if ($delete)
            $this->setState(self::FLASH_COUNTERS, array());
        return $flashes;
    }

    /**
     * Returns a flash message.
     * A flash message is available only in the current and the next requests.
     * @param string $key key identifying the flash message
     * @param mixed $defaultValue value to be returned if the flash message is not available.
     * @param boolean $delete whether to delete this flash message after accessing it.
     * Defaults to true.
     * @return mixed the message message
     */
    public function getFlash($key, $defaultValue = null, $delete = true)
    {
        $value = $this->getState(self::FLASH_KEY_PREFIX . $key, $defaultValue);
        if ($delete)
            $this->setFlash($key, null);
        return $value;
    }

    /**
     * Stores a flash message.
     * A flash message is available only in the current and the next requests.
     * @param string $key key identifying the flash message
     * @param mixed $value flash message
     * @param mixed $defaultValue if this value is the same as the flash message, the flash message
     * will be removed. (Therefore, you can use setFlash('key',null) to remove a flash message.)
     */
    public function setFlash($key, $value, $defaultValue = null)
    {
        $this->setState(self::FLASH_KEY_PREFIX . $key, $value, $defaultValue);
        $counters = $this->getState(self::FLASH_COUNTERS, array());
        if ($value === $defaultValue)
            unset($counters[$key]);
        else
            $counters[$key] = 0;
        $this->setState(self::FLASH_COUNTERS, $counters, array());
    }

    /**
     * @param string $key key identifying the flash message
     * @return boolean whether the specified flash message exists
     */
    public function hasFlash($key)
    {
        return $this->getFlash($key, null, false) !== null;
    }

    /**
     * Changes the current user with the specified identity information.
     * This method is called by {@link login} and {@link restoreFromCookie}
     * when the current user needs to be populated with the corresponding
     * identity information. Derived classes may override this method
     * by retrieving additional user-related information. Make sure the
     * parent implementation is called first.
     * @param mixed $id a unique identifier for the user
     * @param string $name the display name for the user
     * @param array $states identity states
     */
    protected function changeIdentity($id, $name, $states)
    {
        Yii::app()->getSession()->regenerateID(true);
        $this->setId($id);
        $this->setName($name);
        $this->loadIdentityStates($states);
    }

    /**
     * Retrieves identity states from persistent storage and saves them as an array.
     * @return array the identity states
     */
    protected function saveIdentityStates()
    {
        $states = array();
        foreach ($this->getState(self::STATES_VAR, array()) as $name => $dummy)
            $states[$name] = $this->getState($name);
        return $states;
    }

    /**
     * Loads identity states from an array and saves them to persistent storage.
     * @param array $states the identity states
     */
    protected function loadIdentityStates($states)
    {
        $names = array();
        if (is_array($states)) {
            foreach ($states as $name => $value) {
                $this->setState($name, $value);
                $names[$name] = true;
            }
        }
        $this->setState(self::STATES_VAR, $names);
    }

    /**
     * Updates the internal counters for flash messages.
     * This method is internally used by {@link CWebApplication}
     * to maintain the availability of flash messages.
     */
    protected function updateFlash()
    {
        $counters = $this->getState(self::FLASH_COUNTERS);
        if (!is_array($counters))
            return;
        foreach ($counters as $key => $count) {
            if ($count) {
                unset($counters[$key]);
                $this->setState(self::FLASH_KEY_PREFIX . $key, null);
            } else
                $counters[$key]++;
        }
        $this->setState(self::FLASH_COUNTERS, $counters, array());
    }

    /**
     * Updates the authentication status according to {@link authTimeout}.
     * If the user has been inactive for {@link authTimeout} seconds, or {link absoluteAuthTimeout} has passed,
     * he will be automatically logged out.
     * @since 1.1.7
     */
    protected function updateAuthStatus()
    {
        if (($this->authTimeout !== null || $this->absoluteAuthTimeout !== null) && !$this->getIsGuest()) {
            $expires = $this->getState(self::AUTH_TIMEOUT_VAR);
            $expiresAbsolute = $this->getState(self::AUTH_ABSOLUTE_TIMEOUT_VAR);

            if ($expires !== null && $expires < time() || $expiresAbsolute !== null && $expiresAbsolute < time())
                $this->logout(false);
            else
                $this->setState(self::AUTH_TIMEOUT_VAR, time() + $this->authTimeout);
        }
    }

    /**
     * Performs access check for this user.
     * @param string $operation the name of the operation that need access check.
     * @param array $params name-value pairs that would be passed to business rules associated
     * with the tasks and roles assigned to the user.
     * Since version 1.1.11 a param with name 'userId' is added to this array, which holds the value of
     * {@link getId()} when {@link CDbAuthManager} or {@link CPhpAuthManager} is used.
     * @param boolean $allowCaching whether to allow caching the result of access check.
     * When this parameter
     * is true (default), if the access check of an operation was performed before,
     * its result will be directly returned when calling this method to check the same operation.
     * If this parameter is false, this method will always call {@link CAuthManager::checkAccess}
     * to obtain the up-to-date access result. Note that this caching is effective
     * only within the same request and only works when <code>$params=array()</code>.
     * @return boolean whether the operations can be performed by this user.
     */
    public function checkAccess($operation, $params = array(), $allowCaching = true)
    {
        if ($allowCaching && $params === array() && isset($this->_access[$operation]))
            return $this->_access[$operation];

        $access = Yii::app()->getAuthManager()->checkAccess($operation, $this->getId(), $params);
        if ($allowCaching && $params === array())
            $this->_access[$operation] = $access;

        return $access;
    }
}
